1. Field of the Invention
The present invention is related, in general, to a video image data archiver, in particular to a video image data archiver which compresses video image data, and stores the compressed video image data in a recording medium.
2. Description of the Related Art
Storing video image data in a recording medium, such as a CD-ROM (compact disc read only memory) and a hard disk drive, often requires compression of the video image data, because of the large size thereof. Compression of video image data is often achieved by DCT (discrete cosine transformation). The data compression techniques using DCT have been widely used as internationally standardized data compression methods, such as MPEG1 (moving picture expert group 1) and MPEG2.
Japanese unexamined patent application No. P2000-333169A discloses a video image data encoder which allows video image data to be recorded in a recording medium at variable bit rates so that the quality of the recorded moving picture is appropriately controlled.
The disclosed video image data encoder executes real-time record of a video image data at variable bit rates into a storage medium which has a fixed storage capacity. The video image data encoder includes a controller, a quantizer, and an inverse-quantizer. The controller disposed obtains a size and a recording time of original data to be sequentially recorded in the storage medium. The controller determines the remaining storage capacity and recording time of the storage medium and calculates the subsequent target bit rate. The controller controls a quantization step size used by the quantizer 111 and an inverse-quantizer so that the variable bit rate of the record data does not exceed the target bit rate.
Other techniques for compressing moving picture data with variable bit rates are disclosed in Japanese Unexamined Patent Application No. P2000-23155A, P2000-341627, and P2002-27479.
An video image data is to be compressed so that the whole of the compressed video image data is surely stored in a recording medium whose storage capacity is finite. This may be achieved by reducing data size of the compressed video data. However, reducing data size is often undesirably accompanied by degradation of the image quality.
Therefore, a need exists to provide a video image data compression archiver which enables the whole of the compressed video image data to be recorded in a recording medium while improving the image quality of the compressed video image data as far as possible.
Especially, this is the case when the remaining storage capacity of the recording medium is suddenly increased or decreased. As for the case when a hard disk drive is used as a recording medium in a computer system, for example, the free area of the hard disk drive may be increased or decreased by an application used in the computer system. It would be advantageous if a video image data compression archiver develops compressed video image data to surely store the whole of it in a recording medium, so that the image quality of the compressed video image data is appropriately adjusted in response to the storage capacity of the recording medium being suddenly increased or decreased.
The same goes for a sudden change in a recording time and/or a number of frames of video image data to be archived. As for the case that video image data of a broadcast of a baseball game is archived in a recording medium, for example, the recording time and the number of the frames of the video image data may be suddenly increased because of the extra inning(s) of the baseball game. It would be advantageous if a video image data compression archiver develops compressed video image data to surely store the whole of it in a recording medium, so that the image quality of the compressed video image data is appropriately adjusted in response to the recording time and/or the number of the frames being suddenly increased or decreased.